WO2013051298A1

WO2013051298A1 - Suspension device for vehicle

Info

Publication number: WO2013051298A1
Application number: PCT/JP2012/054976
Authority: WO
Inventors: 松田　靖之; 大輔郡司
Original assignee: 日本精工株式会社
Priority date: 2011-05-16
Filing date: 2012-02-28
Publication date: 2013-04-11
Also published as: JP2012254784A; CN103534109A; US8944439B2; EP2711212A4; US20140091538A1; CN103534109B; EP2711212B1; EP2711212A1; JP6035852B2

Abstract

　An upper arm (4b), which constitutes a suspension device for a vehicle, is configured from: a casing (12) which is supported in a manner so as to be able to oscillate relative to a vehicle body; a pair of screw shafts (20) which are supported by the casing (12) in a manner so as to be able to move only in the axial direction; a pair of screw nuts (21) which engage with the perimeters of the screw shafts (20), and which are supported by the casing (12) in a manner so as to be only able to rotate; a worm reduction gear (14) which rotates the screw nuts (21); and a pair of link arms (29a), the base-end sections of which are connected to the tip sections of the screw shafts (20), the tip end sections of which are connected to a knuckle (3), in a manner so as to be able to rotate around the vertical axis of the vehicle. The screw shafts (20) are moved in opposite directions from one another in the axial direction, the angle by which the pair of link arms (29a) are open is altered, and the entire length of the upper arm (4b) relative to the width-wise direction of the vehicle body is altered.

Description

Vehicle suspension system

The present invention relates to a double wishbone type vehicle suspension system in which the camber angle can be appropriately changed according to the traveling state of the vehicle.

Conventionally, various structures are known as suspension devices for vehicles such as passenger cars. Among them, in recent years, a double wishbone type suspension device having a high degree of design freedom and excellent road surface followability has been adopted in many types of vehicles such as luxury cars and sports cars. Fig. 4 shows the conventional structure of a double wishbone suspension system, described in Takeshi Hosokawa's "Mechanical and Mechanism Guide for Cars" (Grand Prix Publishing Co., Ltd., issued on January 10, 2003, page 207). A first example is shown.

The knuckle 3 that rotatably supports the wheel 1 via the bearing unit 2 is supported by an upper arm 4 and a lower arm 5 that constitute a double wishbone suspension so as to be swingable with respect to a vehicle body (not shown). Of these, the upper arm 4 is formed of a so-called A-shaped frame having a substantially A-shape, and has a tip portion (an end on the outside in the width direction of the vehicle body and an end on the right side in FIG. 4 when attached to the vehicle body). The upper knuckle 3 is connected to the upper end via an upper ball joint 6. Further, the base end portion of the upper arm 4 (the end portion on the center side in the width direction of the vehicle body and the left end portion in FIG. 4 when attached to the vehicle body) is supported to be swingable by a pivot with respect to the vehicle body (not shown). Has been.

On the other hand, the lower arm 5 is also made of a so-called A-shaped frame having a substantially A shape, and its tip is connected to the lower end of the knuckle 3 via the lower ball joint 7. Further, the base end portion of the lower arm 5 is supported by a pivot so as to be swingable with respect to a vehicle body (not shown). The lower arm 5 supports a lower end portion of a shock absorber 8 whose upper end portion is fixed to the vehicle body so as to be swingable by a pivot.

In the case of such a conventional double wishbone suspension, the upper arm 4 and the lower arm 5 having different lengths are used (generally, the lower arm is made longer than the upper arm) so that the camber angle is predetermined. Setting the angle is done. However, in the case of a suspension device having a conventional structure, the camber angle set in advance in this way cannot be changed according to the traveling state of the vehicle.

Incidentally, the turning motion of the vehicle is mainly caused by the lateral force of the tire, although it is also caused by the difference in driving force between the left and right wheels. This tire lateral force is generally determined by the driver operating the steering wheel and changing the toe angle (steering angle) of the front wheels via the steering gear, so that the vehicle travels between the direction of travel and the direction of the tire. This is caused by causing a shift (slip angle). It is known that the tire lateral force is affected by a change in camber angle in addition to the toe angle. FIG. 5 shows the relationship between the tire lateral force and the slip angle when the camber angle is used as a parameter, obtained by simulation by the present inventors. As apparent from FIG. 5, even when the slip angle is constant, the tire lateral force can be changed by changing the camber angle. Therefore, if the magnitude of the tire lateral force can be adjusted by changing the camber angle, it is possible to further improve the turning performance of the vehicle, and hence the straight running performance.

Japanese Patent Application Laid-Open No. 10-264636 discloses a double wishbone type vehicle suspension device that can change the camber angle according to the traveling state of the vehicle. FIG. 6 shows a second example of the conventional structure described in this document. In the case of the second example of this conventional structure, extendable

hydraulic cylinders

9 and 10 are provided in the middle between the upper arm 4a and the lower arm 5a, respectively, so that the total length of each of the upper arm 4a and the lower arm 5a can be changed. If it is recognized that it is necessary to change the camber angle by detecting the side slip angle of the wheel 1 by a sensor (not shown), each hydraulic cylinder is passed through a hydraulic pipe or various valves from a hydraulic pump installed in the engine room. A predetermined amount of pressure oil is supplied to 9 and 10. Thereby, the camber angle of the wheel 1 is changed by changing the total length of each of the upper arm 4a and the lower arm 5a. According to the suspension device of the second example having such a conventional structure, the magnitude of the tire lateral force can be adjusted, and the turning performance of the vehicle and consequently the straight running performance can be improved.

However, in the case of the second example of the conventional structure, it is necessary to provide a hydraulic pump, hydraulic piping, various valves and the like in order to enable the camber angle to be changed, and the upper arm 4a and the lower arm 5a have hydraulic pressures respectively.

Cylinders

9 and 10 need to be provided. For this reason, there is a problem that not only the structure for making the camber angle variable is complicated, but also the suspension device is increased in size and weight. In particular, an increase in the weight of the upper arm 4a and the lower arm 5a leads to an increase in unsprung load, which is not desirable from the viewpoint of improving the running performance of the vehicle, centering on ride comfort and running stability. In addition, since the camber angle is controlled hydraulically, there is a problem that controllability and responsiveness are poor, and further, power loss of the engine increases.

Note that Japanese Patent Laid-Open No. 2009-107533 and Japanese Patent Laid-Open No. 2010-83212 also disclose a camber angle adjusting device for changing the magnitude of the camber angle in accordance with the traveling state of the vehicle. However, in the case of the devices described in these documents as well, the structure for making the camber angle variable is complex, as in the device disclosed in Japanese Patent Laid-Open No. 10-264636, and the suspension device is increased in size. This causes a problem of increasing the weight. As a technique related to the present invention, there is a load measuring device for measuring a load applied to a bearing unit, which is disclosed in Japanese Patent Application Laid-Open No. 2005-98771.

Japanese Patent Laid-Open No. 10-264636 JP 2009-107533 A JP 2010-83212 A Japanese Patent Laid-Open No. 2005-98771

In view of the circumstances as described above, the present invention provides a suspension for a vehicle in which the camber angle can be changed as appropriate in accordance with the traveling state of the vehicle without causing complication of the device and accompanying increase in size and weight of the device. The object is to realize the device with a simple structure.

The vehicle suspension system of the present invention is basically connected to the upper part of a knuckle on which wheels are rotatably supported via an upper joint, similarly to the conventional double wishbone type vehicle suspension system. An upper arm having a base end portion supported so as to be swingable in the vertical direction with respect to the vehicle body, a tip portion connected to the lower portion of the knuckle via a lower joint, and the vehicle body And a lower arm having a base end portion supported so as to be swingable in the vertical direction.

The vehicle suspension device of the present invention is characterized by the structure of the upper arm among them. That is, the upper arm of the vehicle suspension device of the present invention is
A casing supported to be swingable in the vertical direction with respect to the vehicle body;
A pair of screw shafts supported so as to be movable only in the axial direction with respect to the casing in a state of being coaxially arranged in the longitudinal direction of the vehicle body;
A pair of screw nuts respectively engaged around the pair of screw shafts and supported to be rotatable only with respect to the casing;
A worm wheel that is freely combined with the pair of screw nuts to rotate in synchronization with these screw nuts;
A worm having worm teeth meshing with the worm wheel;
An electric motor supported by the casing and capable of rotationally driving the worm in both directions;
The front end portion and the base end portion are respectively connected, and the base end portions are connected to the respective front end portions of the pair of screw shafts so as to be rotatable around the vertical axis of the vehicle body. , And a pair of link arms, each of which is connected to the upper joint so as to be rotatable about a vertical axis of the vehicle body.

In the vehicle suspension device of the present invention, the worm is rotationally driven by the electric motor to advance and retract the pair of screw shafts in directions opposite to each other with respect to the axial direction so that the opening angle of the pair of link arms is increased. By changing the length, the length of the pair of link arms in the width direction of the vehicle body, that is, the total length of the upper arms in the width direction of the vehicle body is changed.

A feed screw mechanism is configured by a combination of the pair of screw shafts and the pair of screw nuts. As the feed screw mechanism, in each combination of the pair of screw shafts and the pair of screw nuts, female threads formed on the inner peripheral surfaces of the respective screw nuts are formed on the outer peripheral surfaces of the respective screw shafts. A sliding screw type feed screw mechanism slidably engaged with the formed male screw can be employed.

Alternatively, as the feed screw mechanism, in each combination of the pair of screw shafts and the pair of screw nuts, an outer diameter side ball screw groove formed on an inner peripheral surface of each screw nut; It is also possible to adopt a ball screw type feed screw mechanism in which an inner diameter side ball screw groove formed on the outer peripheral surface of each screw shaft is engaged through a plurality of balls arranged therebetween. it can.

Further, a rotation prevention mechanism is provided between the pair of screw shafts and the casing to prevent relative rotation of the screw shafts with respect to the casing while allowing axial displacement of the screw shafts. Is preferred.

The worm wheel is preferably made of synthetic resin. Further, it is preferable that a reduction mechanism that increases the power of the electric motor and transmits it to the worm is provided between the worm and the electric motor.

According to the present invention configured as described above, it is possible to realize a vehicle suspension device capable of appropriately changing the camber angle in accordance with the traveling state of the vehicle with a simple structure, and to reduce the size and weight of the entire device. it can. That is, in the case of the vehicle suspension system of the present invention, a structure for making the entire length of the upper arm (the length of the link arm in the width direction of the vehicle body) variable is integrated in the upper arm itself. For this reason, about the other members, such as a lower arm, the thing similar to the case of a conventional structure can be used. Further, it is not necessary to install a member such as a hydraulic pump required in the second example of the conventional structure on the vehicle body side (for example, the engine room). Furthermore, the total length of the upper arm can be changed by a simple configuration combining a feed screw mechanism, a worm speed reducer, and a link mechanism.

Therefore, according to the vehicle suspension device of the present invention, it is possible not only to further improve the turning performance and straight running performance of the vehicle, but also to sufficiently suppress an increase in unsprung load, and to improve riding comfort and travel performance. It is also possible to improve the running performance of the vehicle, focusing on stability. Furthermore, since camber angle control (upper arm full length control) is performed by energization control of the electric motor, controllability and responsiveness are superior to those of the hydraulic type, and no engine power loss occurs. In addition, since power (energy) is consumed only during driving, energy saving can be achieved. Also, the camber angles of the left and right wheels can be controlled independently.

FIG. 1 is a front view schematically showing a vehicle suspension apparatus according to an embodiment of the present invention in a state where wheels are suspended from a vehicle body. 2 is a plan view of the upper arm taken out from the vehicle suspension shown in FIG. 1 as viewed from above the vehicle. FIG. 2 (A) shows a state where the overall length is maximized, and FIG. The state where the total length is minimized is shown respectively. FIG. 3 is a schematic view showing the worm speed reducer taken out from the vehicle suspension shown in FIG. FIG. 4 is a perspective view schematically showing a vehicle suspension device of a first example having a conventional structure. FIG. 5 is a graph showing the relationship between the tire lateral force and the slip angle when the camber angle is used as a parameter, obtained by simulation. FIG. 6 is a front view schematically showing a vehicle suspension device of a second example having a conventional structure.

[Example of Embodiment]
1 to 3 show an example of an embodiment of the present invention. The feature of this example is that, with regard to a double wishbone type vehicle suspension system, a structure for making the entire length of the upper arm 4b variable is integrated in the upper arm 4b itself, so that the camber angle γ is set according to the traveling state of the vehicle. The point is that it can be appropriately changed. The lower arm 5 and other members are the same as in the first example of the conventional structure shown in FIG. Therefore, hereinafter, the description will focus on the structure of the upper arm 4b, which is a characteristic part of this example.

As shown in FIG. 1, also in the case of the vehicle suspension system of this example, a knuckle 3 in which a wheel 1 is rotatably supported via a bearing unit 2 is connected to a vehicle body 11 (see FIG. 1) by an upper arm 4b and a lower arm 5. 2). For this reason, while connecting the front-end | tip part (right end part of FIG. 1 and FIG. 2) of the upper arm 4b to the upper end part of the knuckle 3 via the upper ball joint 6 which is an upper joint, the base end part ( 1 and 2 is supported so as to be swingable with respect to the vehicle body 11. Further, the lower arm 5 is connected to the lower end of the knuckle 3 via a lower ball joint 7 which is a lower joint, and the base end of the lower arm 5 is supported to be swingable with respect to the vehicle body 11. Yes. Normally, ball joints are used as these joints, but other joints including cardan joints are acceptable as long as the joints allow swinging displacement in the respective directions of the respective tip portions of the upper arm 4b and the lower arm 5. A structure can also be adopted.

Particularly in the case of this example, in order to make the entire length of the upper arm 4b variable, the upper arm 4b is composed of a casing 12, a pair of

feed screw mechanisms

13a and 13b, a worm speed reducer 14, and a link mechanism 15. Consists of. Of these, the casing 12 has its base half (the inner half in the width direction, the left half in FIG. 2) disposed in a portion between a pair of mounting portions 16 provided on the vehicle body 11 so as to be separated in the front-rear direction. In this state, these mounting portions 16 are supported by bolts 17 and nuts 18 so as to be swingable in the vertical direction of the vehicle body 11 via rubber bushes 19 and the like. In the case of this example, the center axes of both bolts 17 coincide with the swing center O of the upper arm 4b. Further, feed

screw mechanisms

13a and 13b are arranged in the front-rear direction of the vehicle body 11 inside the front half of the casing 12 (the outer half in the width direction, the right half in FIG. 2). A worm speed reducer 14 is provided at the center of the half in the front-rear direction.

Each feed screw mechanism 13a (13b) comprises a slide screw type feed screw mechanism, and is constituted by a combination of a screw shaft 20a (20b) and a screw nut 21a (21b). The

screw shafts

20 a and 20 b are made of, for example, stainless steel, and are coaxially arranged in the front-rear direction of the vehicle body 11. A spiral male screw is formed on the outer peripheral surface of each

screw shaft

20a, 20b, and the pitch thereof is the same between these

screw shafts

20a, 20b. Further, a non-illustrated non-rotating convex portion is formed on at least a part of the outer peripheral surface of each of the

screw shafts

20a and 20b. Engaged. The rotation prevention mechanism allows axial displacement of the casing 12 but prevents the relative rotation, and the

screw shafts

20a and 20b are supported by the casing 12. In this example, a sliding screw type feed screw mechanism is employed to reduce the number of parts and reduce the weight of the suspension device. However, alternatively, a ball screw type feed screw mechanism is adopted to reduce the torque for rotationally driving the

screw shafts

20a, 20b, thereby reducing the size of the suspension device through the miniaturization of the electric motor. You may make it aim at weight reduction. Further, in this case, it is possible to improve the positioning accuracy of the

screw shafts

20a and 20b and to accurately control the camber angle.

Each of the screw nuts 21a and 21b is made of a synthetic resin such as polyphenylene sulfide, polyamide 66, polyether ether ketone (PEEK), polyacetal, and the like, and a spiral female screw is formed on each inner peripheral surface. In the case of this example, these

screw nuts

21a and 21b are integrally formed in a shape in which their base ends are connected by simultaneous processing by injection molding. Female threads in opposite directions are formed on the inner peripheral surfaces of these

screw nuts

21a and 21b. The screw nuts 21a and 21b having such a structure are supported on the inside of the casing 12 so as to be rotatable only, and the internal threads formed on the inner peripheral surfaces thereof are opposite to the outer peripheral surfaces of the

respective screw shafts

20a and 20b. Each is slidably engaged with a male screw formed in a direction.

As shown in FIG. 3, the worm speed reducer 14 includes a worm wheel 22, a worm 23, an electric motor 24, and a speed reduction mechanism 25. Of these, the worm wheel 22 is made of polyphenylene sulfide, polyamide 66, a synthetic resin such as MC nylon (registered trademark), polyether ether ketone (PEEK), polyacetal, which is a kind of polyamide resin, and screw nuts 21a and 21b. They are arranged concentrically. The synthetic resin can be filled with glass fiber or carbon fiber to improve the strength and rigidity of the worm wheel 22. In the case of this example, the worm wheel 22 is simultaneously processed by injection molding together with the screw nuts 21a and 21b, so that the worm wheel 22 is axially central (the screw nuts 21a and 21b). It is directly formed on the outer peripheral surface of a portion corresponding to the connecting portion connecting the base end portions. Therefore, the worm wheel 22 rotates together with the screw nuts 21a and 21b. As described above, the weight of the suspension device can be reduced by making the worm wheel 22 made of synthetic resin. Alternatively, the worm wheel 22 is configured as a separate body and directly connected to the screw nuts 21a and 21b. Alternatively, it can also be coupled and fixed indirectly through other members. In this case, the degree of freedom in selecting the material of the worm wheel 22 is improved.

The worm 23 is made of metal or synthetic resin, and includes a worm shaft 26 disposed at a position twisted with respect to the

screw shafts

20a and 20b, and worm teeth 27 formed on an outer peripheral surface of an intermediate portion of the worm shaft 26. Composed. The worm teeth 27 of the worm 23 are meshed with the worm wheel 22. In the case of this example, the rotation of the worm hole 22 is prevented from being transmitted to the worm 23 by restricting the twist angle of the worm teeth 27 (setting the twist angle large). Thereby, the total length of the upper arm 4b is not changed by the force applied to the pair of

link arms

29a and 29b constituting the link mechanism 15 from the wheels. Alternatively, the same effect can be obtained by providing the electric motor itself with a braking action.

The electric motor 24 is supported and fixed to the casing 12 by a plurality of (three in the illustrated example) screws 28. Then, the drive shaft (not shown) is rotated in either the forward direction or the reverse direction by switching the energized state. The speed reduction mechanism 25 is composed of a plurality of gears (not shown), and increases the power (torque) of the electric motor 24 and transmits it to the worm shaft 26 of the worm 23. In this example, the reduction mechanism 2 is provided, whereby the electric motor 24 can be reduced in size, so that the vehicle suspension apparatus as a whole can be reduced in size and weight.

The link mechanism 15 includes a pair of

link arms

29 a and 29 b and a connecting member 30. Of these, the pair of

link arms

29a and 29b is made of a forged product such as an iron-based alloy, an aluminum-based alloy, or a magnesium-based alloy, and is formed in a round bar shape that is slightly curved in an arc shape. Further, the connecting member 30 constitutes a socket of the upper ball joint 6, and a lid body 31 that closes the upper portion of the ball housing portion is provided at a substantially central portion thereof. In the case of this example, the base ends of the

link arms

29a and 29b are connected to the tip ends of the

screw shafts

20a and 20b using the joint member 32a in the vertical direction (see FIG. 2). The front and rear ends of the

link arms

29a and 29b are connected to the corners of the connecting member 30 by using joint members 32b. It is connected so as to be rotatable about an axis directed in the direction.

In the case of this example, the wheel 1 is utilized by using an encoder and a load sensor (not shown) arranged in the bearing unit 2 as described in Japanese Patent Laid-Open No. 2005-98771 and conventionally known. The tire lateral force (axial load) applied to the tire is measured. Then, the measured tire lateral force data is sent to a controller (not shown), and the comparison / determination means in the controller determines whether the tire lateral force is excessive or insufficient under the current running condition of the vehicle. Based on this result, energization (energization direction, energization amount) to the electric motor 24 is controlled.

Specifically, the electric motor 24 rotates the worm 23 in a forward direction or a reverse direction by a predetermined number of rotations (rotation angle). Thereby, the screw nuts 21a and 21b are rotated via the worm wheel 22, and the

respective screw shafts

20a and 20b are opposite to each other with respect to the axial direction (the longitudinal direction of the vehicle body, the front and back direction in FIG. 1, the vertical direction in FIG. 2). ) Is advanced or retracted by a predetermined amount. Then, by changing the opening angle of the

link arms

29a and 29b, the length L of the

link arms

29a and 29b in the width direction of the vehicle body 11 (left and right direction in FIGS. 1 and 2) is changed by a predetermined amount (upper arm). Change the total length of 4b). More specifically, as shown in FIG. 2A, when the electric motor 24 is driven so that the projecting amount of the

screw shafts

20a, 20b from the casing 12 becomes small, the

link arms

29a, 29b The opening angle becomes smaller. Thereby, the lengths of these

link arms

29a and 29b in the width direction of the vehicle body 11 are increased (L = L _max ), and the entire length of the upper arm 4b is increased. As a result, the distance from the swing center O of the upper arm 4b to the center P of the upper ball joint 6 increases, and the camber angle γ changes. That is, in the case of positive camber, the camber angle is further increased, and in the case of negative camber, the camber angle is decreased. In contrast, as shown in FIG. 2B, when the electric motor 24 is driven so that the protruding amount of the

screw shafts

20a, 20b from the casing 12 is increased, the link arms 28a, 28b are opened. The angle increases. As a result, the lengths of the

link arms

29a and 29b in the width direction of the vehicle body 11 are reduced (L = L _min ), and the overall length of the upper arm 4b is shortened. As a result, the distance from the swing center O of the upper arm 4b to the center P of the upper ball joint 6 is reduced, and the camber angle γ is changed. That is, in the case of positive camber, the camber angle is reduced, and in the case of negative camber, the camber angle is further increased.

The vehicle suspension device of this example can operate as described above, so that the camber angle γ can be appropriately changed according to the traveling state of the vehicle, and the generated tire lateral force can be adjusted. In FIG. 2B, the protruding amounts of the

screw shafts

20a and 20b are drawn exaggerated from the actual case for clarity of explanation. In actual cases, it is not necessary to increase the protrusion amount to the extent shown in FIG. Moreover, each movable part is covered with a cover or bellows (not shown) to prevent foreign matters such as muddy water from adhering to these parts.

As described above, in the case of the vehicle suspension system of this example, the structure for making the entire length of the upper arm 4b variable is integrated in the upper arm 4b itself, and components such as a hydraulic pump on the vehicle body 11 side are integrated. Installation is unnecessary. Furthermore, the upper arm 4b can be changed in its overall length by a simple configuration in which a pair of

feed screw mechanisms

13a and 13b, a worm speed reducer 14, and a link mechanism 15 are combined. In the present invention, with such a structure, a vehicle suspension device capable of appropriately changing the camber angle γ according to the traveling state of the vehicle is realized with a simple structure, and the size and weight are reduced. Such a structure not only can further improve the turning performance and straight-ahead performance of the vehicle, but also sufficiently suppress the increase in unsprung load and drive the vehicle with a focus on ride comfort and running stability. The performance can be improved.

In the case of this example, since the camber angle γ is controlled by the electric type (control of the entire length of the upper arm 4b), controllability and responsiveness are superior to those of the hydraulic type, and engine power loss also occurs. No need. Furthermore, since power (energy) is consumed only during driving, energy saving can be achieved.

In addition, since the entire length of the upper arm 4b, not the lower arm 5, is variable, the camber angle γ can be changed without difficulty even when the vehicle is stopped. Furthermore, the camber angles of the left and right wheels can be independently controlled by applying the vehicle suspension system of the present invention to the left and right wheels.

DESCRIPTION OF SYMBOLS 1 Wheel 2 Bearing unit 3

Knuckle

4, 4a,

4b Upper arm

5, 5a Lower arm 6 Upper ball joint 7 Lower ball joint 8 Shock absorber 9 Hydraulic cylinder 10 Hydraulic cylinder 11 Car body 12

Casing

13a, 13b Feed screw mechanism 14 Worm speed reducer 15 Link Mechanism 16 Mounting portion 17 Bolt 18 Nut 19

Bush

20a,

20b Screw shaft

21a, 21b Screw nut 22 Worm wheel 23 Worm 24 Electric motor 25 Deceleration mechanism 26 Worm shaft 27 Worm tooth 28

Screw

29a, 29b Link arm 30 Connecting member 31

Housing portion

32a, 32b Joint member

Claims

An upper arm having a distal end portion connected to an upper portion of a knuckle on which wheels are rotatably supported via an upper joint, and a base end portion supported so as to be swingable in a vertical direction with respect to a vehicle body, and the knuckle A lower arm having a distal end portion connected through a lower joint and a base end portion supported so as to be swingable in the vertical direction with respect to the vehicle body,
The upper arm is
A casing supported to be swingable in the vertical direction with respect to the vehicle body;
A pair of screw shafts supported so as to be movable only in the axial direction with respect to the casing in a state of being coaxially arranged in the longitudinal direction of the vehicle body;
A pair of screw nuts respectively engaged around the pair of screw shafts and supported to be rotatable only with respect to the casing;
A worm wheel that is freely combined with the pair of screw nuts to rotate in synchronization with these screw nuts;
A worm having worm teeth meshing with the worm wheel;
An electric motor supported by the casing and capable of rotationally driving the worm in both directions;
The front end portion and the base end portion are respectively connected, and the base end portions are connected to the respective front end portions of the pair of screw shafts so as to be rotatable around the vertical axis of the vehicle body. A pair of link arms each of which is connected to the upper joint so as to be rotatable around an axis in the vertical direction of the vehicle body,
The worm is rotationally driven by the electric motor, the pair of screw shafts are advanced and retracted in directions opposite to each other with respect to the axial direction, and the opening angle of the pair of link arms is changed. A suspension system for a vehicle, wherein a length of the pair of link arms is changed.
In each combination of the pair of screw shafts and the pair of screw nuts, a female screw formed on the inner peripheral surface of each screw nut slides on a male screw formed on the outer peripheral surface of each screw shaft. The suspension device for a vehicle according to claim 1, wherein a sliding screw type feed screw mechanism is configured by being engaged with each other.
In each combination of the pair of screw shafts and the pair of screw nuts, outer diameter side ball screw grooves formed on the inner peripheral surfaces of the respective screw nuts and outer peripheral surfaces of the respective screw shafts. The ball screw type feed screw mechanism is configured by engaging the inner diameter side ball screw groove with a plurality of balls disposed between them. Suspension device.
A detent mechanism is provided between the pair of screw shafts and the casing to prevent relative rotation of the screw shafts with respect to the casing while allowing axial displacement of the screw shafts. The vehicle suspension device according to any one of claims 1 to 3.
The vehicle suspension device according to any one of claims 1 to 4, wherein the worm wheel is made of a synthetic resin.
The suspension for a vehicle according to any one of claims 1 to 5, further comprising a reduction mechanism that increases power of the electric motor and transmits the power to the worm between the worm and the electric motor. apparatus.